/*
 *  Copyright 2013 National Institute of Advanced Industrial Science and Technology
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.sss.util;

import java.io.PrintStream;

public class Hexdump {
  private static final String NL = System.getProperty("line.separator");
  private static final int NL_LENGTH = NL.length();
  private static final char[] SPACE_CHARS = {
    ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
    ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
    ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
    ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
    ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
    ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ' };
  public static final char[] HEX_DIGITS = {
    '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
  /**
   * Generate "hexdump" output of the buffer at src like the following:
   *
   * <p><blockquote><pre>
   * 00000: 04 d2 29 00 00 01 00 00 00 00 00 01 20 45 47 46  |..)......... EGF|
   * 00010: 43 45 46 45 45 43 41 43 41 43 41 43 41 43 41 43  |CEFEECACACACACAC|
   * 00020: 41 43 41 43 41 43 41 43 41 43 41 41 44 00 00 20  |ACACACACACAAD.. |
   * 00030: 00 01 c0 0c 00 20 00 01 00 00 00 00 00 06 20 00  |..... ........ .|
   * 00040: ac 22 22 e1                                      |."".            |
   * </blockquote></pre>
   */
  public static void hexdump(PrintStream ps, byte[] src, int srcIndex,
    int length) {
    if (length == 0) {
      return;
    }
    int s = length % 16;
    int r = (s == 0) ? length / 16 : length / 16 + 1;
    char[] c = new char[r * (74 + NL_LENGTH)];
    char[] d = new char[16];
    int i;
    int si = 0;
    int ci = 0;
    do {
      toHexChars(si, c, ci, 5);
      ci += 5;
      c[ci++] = ':';
      do {
        if (si == length) {
          int n = 16 - s;
          System.arraycopy(SPACE_CHARS, 0, c, ci, n * 3);
          ci += n * 3;
          System.arraycopy(SPACE_CHARS, 0, d, s, n);
          break;
        }
        c[ci++] = ' ';
        i = src[srcIndex + si] & 0xFF;
        toHexChars(i, c, ci, 2);
        ci += 2;
        if (i < 0 || Character.isISOControl((char) i)) {
          d[si % 16] = '.';
        }
        else {
          d[si % 16] = (char) i;
        }
      }
      while ((++si % 16) != 0); // do
      c[ci++] = ' ';
      c[ci++] = ' ';
      c[ci++] = '|';
      System.arraycopy(d, 0, c, ci, 16);
      ci += 16;
      c[ci++] = '|';
      NL.getChars(0, NL_LENGTH, c, ci);
      ci += NL_LENGTH;
    }
    while (si < length);        // do
    ps.println(c);
  }
  /**
   * This is the same as {@link jcifs.util.Hexdump#toHexString(int val, int
   * size)} but provides a more practical form when trying to avoid {@link
   * java.lang.String} concatenation and {@link java.lang.StringBuffer}.
   */
  public static void toHexChars(int val, char dst[], int dstIndex, int size) {
    while (size > 0) {
      int i = dstIndex + size - 1;
      if (i < dst.length) {
        dst[i] = HEX_DIGITS[val & 0x000F];
      }
      if (val != 0) {
        val >>>= 4;
      }
      size--;
    }
  }

  public static void toHexChars(long val, char dst[], int dstIndex,
    int size) {
    while (size > 0) {
      dst[dstIndex + size - 1] = HEX_DIGITS[(int) (val & 0x000FL)];
      if (val != 0) {
        val >>>= 4;
      }
      size--;
    }
  }
}
